Tesla Model 3 Battery Pack Teardown

The Tesla Model 3 has been available for almost a year now, and hackers and tinkerers all over the world are eager to dig into Elon’s latest ride to see what makes it tick. But while it’s considerably cheaper than the Model S that came before it, the $35,000+ USD price tag on the new Tesla is still a bit too high to buy one just to take it apart. So for budget conscious grease monkeys, the only thing to do is wait until somebody with more money than you crashes one and then buy the wreckage cheaply.

Tesla Model 3 battery monitor board

Which is exactly what electric vehicle connoisseur [Jack Rickard] did. He bought the first wrecked Model 3 he could get his hands on, and proceeded to do a lengthy teardown on what’s arguably the heart and soul of the machine: its 75 kWh battery pack. Along the way he made some interesting discoveries, and gained some insight on to how Tesla has been able to drop the cost of the Model 3 so low compared to their previous vehicles.

On a Tesla, the battery pack is a large flat panel which takes up effectively the entire underside of the vehicle. To remove it, [Jack] and his assistant raise the wreck of the Model 3 up on a standard lift and then drop the battery down with a small lift table. Here the first differences are observed: while the Model S battery was made for rapid swapping (a feature apparently rarely utilized in practice), the battery in the Model 3 battery is obviously intended to be a permanent piece of the car; removing it required taking out a good portion of the interior.

With the battery out of the car and opened up, the biggest change for the Model 3 becomes apparent. The battery pack actually contains the charger, DC-DC converter, and battery management system in one integrated unit. Whereas on the Model S these components were installed in the vehicle itself, on the Model 3, most of the primary electronics are stored in this single module.

That greatly reduces the wiring and complexity of the car, and [Jack] mentions the only significant hardware left inside the Model 3 (beyond the motors) would be the user interface computer in the dashboard. When the communication protocol for this electronics module is reverse engineered, it may end up being exceptionally useful for not only electric vehicle conversions but things like off-grid energy storage.

52 thoughts on “Tesla Model 3 Battery Pack Teardown”

Any idea why the circular thing on the circuit board in the photo? It seems strange to see such a large area unpopulated by components. There must be some reason for that.

Also, does the Model 3 have a separate 12v lead acid battery, or does it somehow drop the voltage from the main battery to 12v? (The earlier article about buck converter efficiencies got me wondering about this as well).

Looking at the board, in the circular area there is only a connector, and the ring around it, is completely void of copper, which makes me think that the annular around the connector is where a rubber seal touches the board and helps make the battery water tight.
Looking further at the board, a second connector can be noticed just below the circular area, which makes me think that I am completely wrong, or that the second connector doesn’t interface to the outside of the battery enclosure.

Looking closely at the video, the pictured board is probably from one of the “edge” battery subunits. You can see them disconnecting cross-connections between the subunits, which look like they plug into the lower connector(The center two subunits have three connectors each), and then the upper connector goes to the section “above” the battery subunits. Possibly communication between the subunit BMSs, for charge/discharge coordination?

Alright, I feel bad leaving it vague like that. So, in the article linked in another comment you’ll see that with the orange cover plate on, there’s a translucent seal that sits where this dead space is. that goes up to the “penthouse.” They didn’t post tear down photos showing the inside of the “penthouse” so I can’t really say what lives up there and plugs into it. Presumably something circular. A “saucer” if you will.

There’s only one DC source. Issues isolating the two sources aside, even if there are efficiency issues you’d still spend less money and effort shifting your voltage to 12V vs. adding an entirely separate battery. They’re also (almost) certainly using a SMPS, not a buck converter. These are relatively more efficient but more costly in terms of components due to the signal transformer. There’s a couple places that transformer might live… That sure looks like a toroidal transformer on the board that lives in the silver can they found in the “penthouse.” http://evtv.me/evtv-word-press/wp-content/uploads/2018/05/chargercontrolboard-1024×452.png

Expanding on that, it makes sense the 12V DC output is on that can. It’s the DC-DC board described in the article someone linked below. You’d do all your voltage conversions in one place, seeing as that’s where you have the thermal management at hand to manage the rather intense process of converting… roughly 300+V to something usable outside the drive system hurling the car forward from 0-60MPH in under 3 seconds.

Oh! A final cautionary observation. Rough math on the module voltage and a few other readily available and previously observed specs to find P=IV… don’t take that “penthouse” off lightly. I’ll let someone else calculate arc length but the short version is you don’t want an unmanaged and constant load of basically any kind across all four modules in series. Bad news bears.

Not totally following what spawned this question but I have to point out – POL or point of load converters are a pretty common thing. Also id be willing to bet those 6 terminal rectangles are poted TFs

The reason why you’d want a separate DC source isn’t efficiency, but safety.
In order for the battery pack to be reasonably safe to handle, it needs to have an internal contactor (or 2), and what are you going to power a contactor with if it kills all the traction power? ;-)

Still leaves you with a much less safe system… in the traditional approach, you can simply remove the aux. battery and if the terminals have “0V” on them, you can be pretty sure that the traction stuff is cut off.

The integrated converter approach requires a lot more checking before you can touch the traction stuff…

Model 3 does have a 12 V battery — though Model Y supposedly will do away with it.

I believe I read that there is already some other electric car model on sale that doesn’t have a 12 V battery; but I don’t remember which one…

Either way, there is always a DC-DC converter to generate 12 V: the difference is only in whether the control unit and other 12 V sub-systems are always fed directly by the DC-DC converter from the high-voltage traction battery, or there is a separate 12 V battery that keeps supplying them even while the traction battery is disconnected or empty…

When a wreck is sold at a salvage auction, it likely means it’s beyond refurbishing: it probably sustained structural damage, i.e. it would never be safe to drive again. Only thing you can do is strip it down for parts — which is exactly what those buying them are doing.

And considering the numbers (maybe a couple hundred a years I’d guess?), it’s a niche market.

Those are mainly in the first 15 minutes. (But I skipped lots of it in about 1 minute intervals).
A better reason for not watching it is that it has about 5 minutes with some details, and none about the electronics in the battery itself.

Your “annoyance filter” filters out the perspective of a man who knows the EV industry forwards and backwards. It’s your loss. I agree his tone is a bit winey but he really is a constructive man who knows his beans about EVs, electronics, and even solar power. His youtube videos are NOT for just anyone. You’ve got to have a passion for EVs and a fondness for hacking to appriciate his show. I find his show to be excellent viewing/listening while doing laundry. I can just let it run on while folding and stop and pay close attention when things get fascinating which is quite often. :-)

This got rather personal and I’m rather taken aback by that. I’m impatient with his shortness of breath, not ignorant of his perspective and experience. Insinuating I’m not passionate about hacking and electronics is also funny to me, but that’s mostly because it’s a pretty strange conclusion to come to given available sample data.Though I suppose the flip side of that is that I haven’t rigorously listened to his material and I wouldn’t know where the baseline is. There’s also a fair chance I got impatient with the tear-down because it didn’t cover much I didn’t already know. I should admittedly give the rest of his content a listen to make a more informed decision.

Any attempt to be “personal” towards you was actually genuine sorrow about another soul failing to access what I think is a valuable resource. If there was any offense, it was certainly not my intention and you have my apologies. With that handled, in the context of watching this and other videos by Jack, it really is good to keep one’s self busy doing something very basic while listening/watching, folding laundry, putting together puzzles, or sorting out that 50lb box of assorted resistors you’ve been keeping for decades. :-) I’d also make sure I was well rested and caffeinated. :-) He’s a slow talker but chooses his words carefully so it takes some patience. Like, myself he’s from “fly-over-land” and doesn’t speak faster than he can think like so many coastal people do. He usually hits the target dead center when it comes to EVs, solar, and basically anything Elon Musk touches. He made it clear much more than a year ago, for instance, how Solar, Tesla, Space-X, and StarLink (aka SkyNet) are inter-related. Yes, Elon does want to build bases on Mars and the Moon and probably will, but what he is really building is a global satellite based communications network and eventually a fully autonomous system for delivering anyone and anything from anywhere to anywhere else. Remember, Musk was involved with PayPal too, so Elon is building systems that are energy independent with fully automatic manufacturing, transactions, data, parcel, human, and energy delivery. It’s no wonder he’s worried about the “singularity”. He’s putting together most of the pieces. Jack sees it too and so do I although both Jack and I don’t see an impending singularity coming like Elon does. AI isn’t really that far along. Jack’s show is pretty exciting stuff, if you ask me, which makes it amazing how it comes in such a boring YouTube “package”, but Jack’s an engineer by trade, not a snake-oil salesman and that is one of many reasons why I like him. :-) LLAP to all who made it to the end of this posting. :-)

Fair enough Glitch,
Also in addition to my comment not that appropriate to you it seems since you have made a sizable number of on topic comments, apologies if I cast too wide a net. Though I’d guess you’d have received less reaction or none if you included a comment on the video narrator’s style as positive criticism in one your technical comments as an aid overall. So putting what comes across as exclusively prejudice separately in a separate comment probably put “the weighting function over its threshold” and provoked foxpup and I just added a confirmation for the general case ;-)
No offense intended, Cheers

+1 foxpup
There are far too many idle thoughtless criticisms or provoking troll like questions scattered all over the place again on this forum, not helpful. ie The facile one liners with emotional sense reactions depleted of intellect and not going anywhere stifle some shyer folks making new posts – ugh :-(

There’s a lot of details in there that they only discovered after shooting the video.

The “mason jar wearing a cape” logo on the PCBs that they seemed to be unable to figure out the meaning of… it is clearly a battery with a cape, Battman (the logo appears on boards related to the BMS, so Battery Management > Battman is an obvious short hand / pun). There’s other boards in the Tesla with Robin markings on them… Battman and Robin.

My background in Remote Area Power Systems (RAPS) from about 1989 after a decade in industrial control systems for 3 sites in East Malaysia (Sabah; Mendulong, Sukau) Eg. Old archive link of a mid range design – An adaptive alternator (genset starter battery) field driver and RS-232 to Lead Acid 250Amp 300v charger (1998) http://members.iinet.net.au/~erazmus/Power/

So having seen disasters from too close that kill and maim not just staff but (jungle) wildlife too, I’m keen to improve understanding and explore more diverse methods of addressing standard and novel safety issues in the most intrinsic means possible – which hopefully are also a “no-brainer” economically as well both short and long term Eg maintenance cycles etc…

In respect of the Tesla’s design philosophy then are there many or any sizable NTC and PTC type bulk power handling or individual devices employed (presumably with close coupled semiconductor switching) and how widespread and data depth is data logging such as surely down to the cell level that is, beyond the module level etc ?

Cells are connected with tiny fuse wires that will physically blow if current limits are exceeded, without impacting the neighboring cells. The pack as a whole has a couple of contactors that disconnect +/- from the pack. There’s an additional pyro fuse that can be triggered if the contactors manage to weld shut.

At least with youtube there is a good chance that the project will still be online 5-10 years later when you come across it.
The internet is litered with dead links that the wayback doesn’t have catalogued partly due to their stupid robots policy.
Go back and browse the early days of hackaday and see how much is dead links.

I agree with you that youtube misses many of the finer points, but its’ far easier to document something in a video than it is writing it down and drawing pictures then finding somewhere to host it equally for free which doesn’t turn around and screw you and the rest of the internet years down the line like photobucket.

PS: your work PC doesn’t have sound? Maybe because you should be working? Buy some headphones and/or a USB adapter instead of whining about it.
If you give me a location I can spoon feed it to you as well since it appears to be what you really seek.

But YT clips are not searchable. Only the title, overlays, the description, comments and maybe terrible automatic subbing is searchable text.
So if you don’t know exactly what to search for or how something you want to search for is called, you can’t just search for descriptive terms because they will not turn up results (ok, that’s a little over the top).

Fairly recently I stumbled over on of BigClives clips containing information I could’ve used several years ago. His Video was already up when I was looking for such information, but apparently I didn’t figure out the proper search terms then.

IMHO YT clips are compareable to binary blobs in open source projects.
It’s not that easy to extract useful information and repurpose them in other projects (quite similar to the analogy between STL files and binary blobs recently mentioned on another HaD article).

Making videos of a project maybe easy but you’re not documenting it that way. It’s actually a step back from ‘earlier’ days of the internet (with more blogs, wikis etc) because you’re not digitizing the information.
Yes, making your work/project accessible for other people by properly documenting it is a hassle, but if you want it to be of actual use to others video clips are NOT the way to go.

Going back to the example with BigClive: Just imagine all the information he presents properly digitized in a wiki.
All the LED light sources alone would make up a great database of power consumption, power factor, light emitted, driving circuits and so on and so forth (including graphs and eagle files).

True for the time being limroh but, that may well change and fairly soon too for those clips that have audio. Such that code can add a data layer with searchable and time indexed text. Google is certainly well placed to offer that and I seem to recall there is more than one active project on that from around the time google took over your tube too…

There are certainly many opportunities to add other data structure layers beyond simple transcripts as well as a Ai code layer for the situation where robots could acquire you tube videos and learn various tasks and not just simple ones either as the means to combine and correlate lots of videos across many styles can offer something akin to a gestalt like foundation for more advanced machine learning.

Absolutely agreed. I *hate* vlogs, even well put together ones. I get it, I get why it’s done rather than the more tedious task of composition and layout as a good web page or even wiki blog entry. turning on the camera and just running with it is faster, and I assume that those who edit their work find that editing video is faster than doing a writeup.

I’m thankful and grateful for the content creators because they’re often doing this out of their own pockets and out of a desire to share and help others learn. That’s a fantastic goal and something to be celebrated and encouraged, but man I wish there was a way to get the content in a far more digestible, indexable and more “permanent” format.

Model 3 has NOT been available for nearly a year. Although the first 30 were delivered to employees in July, they were for test and development. High profile customers started to get their Model 3s in January of this year. Now June, they have only satisfied 10K of the 500K preorders from March 2016 and don’t plan to satisfy all of them until closer to 2020.

Also, this is not a $35k car. This 75Kw battery is from the $50k car. There’s also the expense of a home charger and install that bumps that price up by another conservative ~$7k.

While it’s true that it hasn’t been available for a year to the general public, your timeline is off too: customer deliveries actually started in December, not January. (And the early production cars delivered to employees and insiders starting in July were for normal use. Development prototypes have been on the roads several months prior.) Either way, the level of availability is irrelevant to the point that it’s been around for a while, and tinkerers are eager to know what’s inside…

The article also never claimed it’s a “$35k car”. It just mentions the “$35,000+ price tag” (notice the “+”) being steep for taking it apart… (And BTW, the long-range version with the 76 kWh battery is supposed to start at $44,000, once the non-premium interior becomes available towards the end of the year or so.)

$7000 for a home charger? Sorry, that’s just bullshit. (Not to mention that counting the cost of a home charger as part of the vehicle price makes about as much sense as counting the cost of a garage…)

I would like to convert a single 24 volt Tesla module to 12 volt by cutting the plate in half. Anyone with experience of the construction of the battery able to say how possible or impossible this would be?

The two BMS devices on the board are off the shelf Linear Technology parts: two 6804s and another two 681Xs ie Robin and Battman. The two purple connections which lead off the BMS are isoSPI which is a duplex ethernet light style communicatinos network used by Linear Technology and apparently Telsa model 3s. I have a blog explaining how to properly interface to the BMS and talk with it as well as code on Github. Adapter board is in testing will be available soon.